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96 GOLF COURSE MANAGEMENT 03.15
Improved understanding
and testing for salinity
tolerance in cool-season
turfgrasses
Paul G. Johnson, Ph.D.
B. Shaun Bushman, Ph.D.
Water is a critical issue for sustainability
of agriculture and urban areas in the North
American West. Golf course superinten
-
dents are frequently asked, or forced, to use
less irrigation water and/or to use water from
lower-quality sources. Yet at the same time,
rapid population growth requires these turf
-
grass areas to do more and be used by more
people. Turfgrass with high quality, greater
salt tolerance and greater drought tolerance
is essential.
Our research has focused on four
questions:
• Which plant measurements are most ef
-
fcient to select for salt tolerance?
• What variation is present for salt toler
-
ance in perennial ryegrass (L olium pe-
renne), Kentucky bluegrass (Poa pra-
tensis) and alkaligrass (Puccinellia)?
• Can alkaligrass be improved for turf
-
grass quality characteristics?
• What genes can be used to differenti
-
ate between salt-tolerant and suscepti-
ble grasses?
It has been diffcult to fnd consistent salt
tolerance in grasses due to interactions of
climatic factors and variability in soil salin
-
ity. Our project is evaluating materials under
controlled but representative conditions to
gain a better understanding of the mecha
-
nisms of salt tolerance.
In 2014 we focused on two parts of the
(Report)
project: (1) a repeat of a feld salinity experi-
ment combining visual, physiological and mo-
lecular evaluations of bluegrass and ryegrass
entries; and (2) continued study of Puccinel
-
lia (alkaligrass) germplasm for turfgrass qual-
ity traits.
In 2014 we repeated feld salinity experi
-
ments that were also conducted in 2013. The
salt treatments were applied overhead as irri
-
gation and were started mid-June with a salt
concentration of 3 decisiemens/meter, in
-
creased to 6 decisiemens/meter in mid-July,
then increased again to 9 decisiemens/meter
in mid- August. This created soil salinity lev
-
els at 0.3 decisiemens/meter in control plots
up to 12 decisiemens/meter in the salt-treated
plots in August.
As expected, salt treatments reduced turf
-
grass quality, but quality reductions were
lower in 2014 than in 2013, likely because of
generally cooler temperatures. Plant growth
was impacted in 2014, ranging from 0% to
greater than 50% reduction in growth due to
salt stress. Studies of gene expression in salt-
stressed plants compared to control plants is
currently under way.
In short, few data were obtained in 2014
on the alkaligrasses evaluated for turfgrass
quality, since most did not survive the high
temperatures in 2013. This gives us little con
-
fdence that these grasses will provide useful
traits in the semi-arid western United States.
Initial evaluation of Puccinellia showed some
potential in turfgrass quality in cool condi
-
tions, but high temperatures in summer ap-
pear most limiting to the species.
However, we did observe consistent salt-
tolerance trends in key Kentucky bluegrass
lines. Gene sequences (alleles or paralogs) in
-
volved in cellular sodium and calcium chan-
neling have been previously identifed and
will be explored with root and shoot collec
-
tions in 2015.
Paul G. Johnson (paul.johnson@usu.edu) is a professor in
the department of plants, soils and climate at Utah State
University, Logan, and B. Shaun Bushman is a research
geneticist at the USDA-ARS Forage & Range Research Lab
in Logan.
Overall plot photograph on July 9, 2014. Visual symptoms of salt stress were mild at this midsummer
date but growth was signifcantly inhibited. Photo by Paul G. Johnson